1. Field of the Invention
The invention relates to a semiconductor device and a manufacturing method thereof. More particularly, the invention relates to a semiconductor device having a side-gate and a manufacturing method thereof.
2. Description of Related Art
Generally, a display is mainly constructed by a thin film transistor (TFT) array substrate, a color filter array substrate and a display medium layer located between said two substrates. In which, the TFT array substrate includes a plurality of pixel units arranged in matrix, each pixel unit includes a TFT and a pixel electrode electrically connected to the TFT. The TFTs are used as switch devices of a display unit. A drain current of the TFT is mainly decided based on a ratio of a width and a length of a channel. Currently, a photolithography process is generally used in manufacturing a top gate TFT structure or a bottom gate TFT structure.
During the photolithography process, the TFT structure is strongly restricted by lithography resolution (i.e., restricted by a wavelength of light source of the device), such that the devices therein cannot be effectively miniaturized. Accordingly, a channel length of a semiconductor channel layer of the TFT cannot be effectively reduced, so that the driving current cannot be effectively increased. Moreover, with the growing demands for improved resolution, reduced response time and increased aperture ratio of the display, the TFT structures are gradually developed toward a trend in reducing size. However, a miniaturized TFT structure is disadvantageous in manufacturing the semiconductor channel layer since it is disadvantageous in reducing the channel length. It may further affect the drain current of the TFT directly thereby affecting the display quality of the display. In addition, a gate is a single-plane structure, which may only function as a unilateral switch and with shading effect instead of proving full functionalities to the semiconductor channel player. In case when a dual gate design is adopted, a number of process masks may be increased, so as to further increase manufacturing costs. Therefore, how to reduce the size of TFT structure while increasing device performance has become a primary issue in developing display.